Viral immunity Flashcards
What is special about host immune response to viruses?
release of type I interferon
how do viruses get recognized by the host immune system?
cytosolic PRRs such as RIG 1 and MDAs, as well as some toll-like receptors
what types of viruses target host immune cells
canine influenza, infectious bursal disease virus, porcine circovirus-2
how does the creation of viral quasi-species increase viral immune escape?
the creation of quasispecies generates high viral diverisity. each round of replication adds a new mutation, so there is an exponential growth in viral diversity
what is antigenic drift?
as a virus replicates, it acquires more mutations leading to changes in genotype/phenotype. this can increase viral defense against the host immune system
Match the trait to the type of virus:
a. high mutation rate
b. lack of proof reading
1. DNA viruses
2. RNA viruses
dna viruses have high mutation rates. RNA viruses lack proofreading
T/F larger genomes have higher rates of mutation
false. smaller genomes mutate faster
what are the two endosomal TLRs that recognize influenza A?
3 and 7
what are the two cytoplasmic PRRs that recognized influenza A
RIG-1 and MDA5
name three ways influenza virus A can evade the immune system
1/ interfering with the RIG-1 pathway, which results in lower IFN-1 release and phagocytosis
2. mutating TCRs on CTLs
3. undergoing antigenic shift, in which the two subtypes (H1N1 and H3N6) can replicate in the host cell to form clones of the parent types, or a mutant type that has one stand from each subtype
what is antigenic shift>
during viral replication in the host cell, multiple subtypes can come together to form a new sybtype that shares a strand of DNA/RNA from both parent subtype
what are the two things that help herpesvirus evade the immune systme
- latency
- reversibility (can reactivate itself into full viral expression)
where does BHV-1 replicate, and where does it establish life-long latency
it replicates in the nasal mucosae, and is latent in the trigeminal neurons and tonsillar lymphoid follicles. Stress in the animal reactivates the virusq
what are some ways PRRSV can evade host defenses
interference with IFN-alpha
Interference with APCs and T cell activation
making decoy epitopes that “trick” neutralizing antibodies
glycosilating their neutralizing epitopes so that antibodies cant get to em
IFN-y secretion is slow, erratic and low in frequency
what is antibody-dependent enhancement of viral infection
the cross linking of complexes (eitehr antigen/antibody or antigen/complement) leads to enhanced infection of susceptible cells
